I was trading an odd lot of SMH thru IB. I sent a market order routed SMART that never got executed. Customer support told me because it was an odd lot, I had to send a marketable limit instead. So I changed to a marketable limit and thousands of shares traded up to 5 cents below my limit but I still wasn't filled. Eventually I just changed to a full lot to get the fill. I've traded odd lots many times in the past and used market orders and never had this happen. Can somebody explain what's going on there? Thanks.